It is well known, in the prior art, that the structural or mechanical characteristics of a support member may be improved with the addition of internal reinforcements. This practice is common in the use of stamp-formed members, wherein internal supports are secured, typically by welding, to the stamp-formed member to provide additional localized loading capabilities. However, with the increased popularity and dimensional accuracy of hydroforming, there has been a growing trend to provide additional sectional stiffness as needed for localized loading.
By way of review, hydroforming is essentially the process of deforming a tubular member to a desired complex tubular shape. To this end, the tubular member is placed between a pair of dies having cavities which define the desired resultant shape of the tube. The ends of the tubular member are accessible through the die and a seal is connected to the ends of the tubular member. Pressurized fluid is then injected into the ends of the tubular member, thereby forcing the tubular member to expand and conform to the shape defined by the die cavity.
To provide additional sectional stiffness in hydroformed members, attempts have been made to form hydroformed members having varying wall thickness. This is typically accomplished by welding multiple tubular sections having varying wall thickness together to form a tubular blank. The tubular blank is then hydroformed to produce a member having additional localized stiffness. However, this method is relatively time-consuming and requires additional process steps of assembling and welding the tubular blanks. Lastly, the additional processing steps may further limit the ability to mass produce such items cost effectively.
Accordingly, there exists a need in the relevant art to provide a method of simply and conveniently forming a hydroformed structural member capable of providing additional sectional stiffness while, simultaneously, minimizing the necessary process steps. Furthermore, there exists a need in the relevant art to provide a method of forming a member having internal hydroformed reinforcements. Still further, there exists a need in the relevant art to provide a hydroformed member having internal reinforcements.